1. Field of the Invention
This invention relates to test probe for Integrated circuit (IC) socket, and in particular, to a reliable and precise test probe for testing and simulating IC sockets as part of the IC burn-in testing.
2. Description of the Related Art
Test probes are used widely in verifying the integrity of the connection between the IC sockets and the circuit boards on which the IC sockets are permanently mounted. First, a test probe is coupled electrically to a testing equipment. Second, the IC device is removed from the IC socket. The other end of the test probe takes the place of the IC device in the socket. Finally, the IC socket and circuit board assembly is tested for proper operation. By burn-in testing, the present invention refers to the simulation of the performance of the IC socket and circuit board assembly in high temperatures ranges.
Much attention has been devoted to the reliability and features of testing equipments used in the testing cycle. It is only recently that the characteristics of the test probe interface began to receive the attention they deserve in the overall quality control process of fabricating IC devices. The increasing failure rates of high value processor and memory chips have prompted the testing professionals to take a closer look at the specifications, reliability, precision and ergonomics of the probing devices because the aforementioned variables are likely sources of errors in the testing process.
Prior art test probes for IC sockets have contact surfaces designed in one of two ways: (1) conductive strips etched on printed circuit boards which are bonded to the side walls of a hard plastic body, or (2) conductive strips laminated onto the side walls of a hard plastic body to serve, such as in the probe design disclosed by Vonder et al in U.S. Pat No, 4,978,912,
The contact surfaces of prior art test probes tend to splay with repeated insertions--a common experience of human operators using them in the burn-in test process. Moreover, the material of the electrical contact surfaces in the prior art probe designs is usually beryllium copper plated with nickel to reduce wear and tear. With repeated insertions, the protective nickel layers wear out. The exposed copper base oxidises easily and results in higher electrical resistance of the contact surfaces. A test probe which is splayed and worn not only fails to simulate the physical dimensions of the IC device, but also introduces errors into the electrical test parameters.